Memory-related response changes in identified visual neurons of a crab (poster)

MARTÍN BERÓN DE ASTRADA, JULIETA SZTARKER AND DANIEL TOMSIC

Nyborg, Dinamarca

Congreso; 7º International Congress of Neuroethology; 2004

International Society of Neuroethology

Ideally, learning related changes should be studied in vivo, however, the assessment of individual cell performance with intracellular techniques is difficult to achieve. We developed a preparation in the crab Chasmagnathus that allows to perform stable intracellular recordings in the intact animal at the same time it is learning a visual associative task. Chasmagnathus visual learning consists of a modification of the crab escape response elicited upon the presentation of a visual danger stimulus, the acquired memory lasts for several days. Recently, we identified a group of lobula-giant movement detector neurons (MDNs) that respond to the training stimulus reflecting the behavioral changes related to acquisition, short- and long-term memory. However, it was not possible to define whether the observed neuronal changes were actually occurring in these MDNs or they were caused by changes in presynaptic neurons. The response of MDNs to the training stimulus is composed by a strong discharge of action potentials superimposed on graded potential (EPSP). To get insights on the site where learning-related plasticity takes place, here we analyze the input-output relationship of the response of MDNs to the training stimulus. Results reveal that the modification of the neuronal output (action potential discharge) caused by training can not be accounted for by changes in the input (EPSP component). Thus, the data supports the notion that plastic changes occurring in MDNs may largely explain the long-term visual memory of the crab.